A Coloring Ring Back Tone (CRBT) service is a service that enables a calling subscriber to hear a CRBT customized by a called subscriber. The called subscriber may search, through a network, for music or sound files provided by a service provider or operator that can be used as CRBTs, and customize certain music or sound files as his/her own CRBT. When the calling subscriber calls the called subscriber, the calling subscriber hears the music or sound file, which replaces the monotonic ring back tone heard when the CRBT service is not customized.
In the conventional art, when customizing a CRBT, the called subscriber must search for and download music or sound files that he/she is interested in before setting the music or sound files as the CRBT. The calling terminal can hear a different CRBT only after the called subscriber changes the CRBT he/she sets. Therefore, in the conventional CRBT service, the calling subscriber can hear a different ringing tone only after the called subscriber changes the ringing tone. Then, for the calling subscriber, the ringing tone is fixed and cannot be updated in real time. Next, the called subscriber must search for, download, and set a ringing tone for changing the ringing tone, which is a complicated operation.